Mr Shahroudi was born in the Iraqi Shi'a stronghold of Najaf of Iranian descent and he came to Iran shortly after the Islamic revolution of 1979.

He has had a low-profile career as scholar, teacher and researcher in the holy city of Qom, but has published many books on Islamic jurisprudence and sits on the Expediency Council, Iran's top constitutional arbitration body.

Hate-figure

Ayatollah Yazdi headed the judiciary since 1989

The departure of Mr Shahroudi's predecessor - a prominent opponent of the reform programme of President Muhammad Khatami - has been welcomed by the reform camp.

Mr Yazdi's dismissal was one of the demands of pro-reform demonstrators in last month's violent rallies.

The violence broke out after students in Tehran protested against the courts' closure of the most popular pro-reform newspaper Salam.

They have not yet reacted to his new appointment.

Iran's Minister of Islamic Guidance and Culture Ataollah Mohajerani said he hoped that under Mr Hashemi's chairmanship no more newspapers would be banned, the Iranian news agency, Irna, reported.

In a separate development, Irna has published the report of an official commission appointed to investigate last month's riots.

The report is highly critical of the actions of the police and right-wing vigilante groups in attacking a student dormitory at Tehran University.

Seven senior police officials are now to stand trial.

Conservative campaign

Correspondents say Iran's supreme leader had been under pressure to appoint a more even-handed figure as head of the judiciary.

Many liberal journalists and Islamic intellectuals allied to President Khatami have been imprisoned by the courts on various charges under Mr Yazdi's jurisdiction.

On the other hand the courts have taken no action against conservative vigilantes who have broken up pro-reform gatherings and attacked dissidents.

Distinguished scholar

Ayatollah Khamenei's decree appointing the new judiciary head was broadcast on Iranian state radio on Saturday.

Pro-reform minister Mohajerani: "I hope no more papers will be banned."

"I hereby appoint your excellency, a distinguished scholar, a befitting figure and a person of both words and deeds to head the Judiciary of the Islamic Republic of Iran," Mr Khamenei was quoted as saying.

The supreme leader called on Mr Hashemi Shahroudi to shorten the legal process and make other improvements to the justice system.

The judiciary's principle responsibilities are "to defend and realise the rights of the oppressed and to make a stand against those who violate the rights of individuals or communities," Mr Khamenei said.

Mr Hashemi Shahroudi was born in Najaf in 1948. As well as his seat on the Expediency Council, he sits on the Council of Guardians which oversees parliament and elections.

He was arrested in Iraq in the 1970s for political activities against the government, and is reported to have been instrumental in the foundation of Iraq's most prominent Shi'a movement opposed to the leadership of President Saddam Hussein, the Supreme Council of the Islamic Revolution in Iraq.